/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.db.mpp.execution.operator.schema;

import org.apache.iotdb.commons.exception.MetadataException;
import org.apache.iotdb.commons.path.PartialPath;
import org.apache.iotdb.commons.path.PathPatternTree;
import org.apache.iotdb.db.metadata.schemaregion.ISchemaRegion;
import org.apache.iotdb.db.metadata.template.Template;
import org.apache.iotdb.db.mpp.common.schematree.ClusterSchemaTree;
import org.apache.iotdb.db.mpp.execution.operator.OperatorContext;
import org.apache.iotdb.db.mpp.execution.operator.source.SourceOperator;
import org.apache.iotdb.db.mpp.plan.planner.plan.node.PlanNodeId;
import org.apache.iotdb.tsfile.read.common.block.TsBlock;
import org.apache.iotdb.tsfile.read.common.block.column.BinaryColumn;
import org.apache.iotdb.tsfile.read.common.block.column.TimeColumn;
import org.apache.iotdb.tsfile.utils.Binary;
import org.apache.iotdb.tsfile.utils.ReadWriteIOUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Optional;

import static org.apache.iotdb.tsfile.read.common.block.TsBlockBuilderStatus.DEFAULT_MAX_TSBLOCK_SIZE_IN_BYTES;

public class SchemaFetchScanOperator implements SourceOperator {

    private static final Logger logger = LoggerFactory.getLogger(SchemaFetchScanOperator.class);

    private final PlanNodeId sourceId;
    private final OperatorContext operatorContext;
    private final PathPatternTree patternTree;
    private final Map<Integer, Template> templateMap;

    private final ISchemaRegion schemaRegion;
    private final boolean withTags;

    private boolean isFinished = false;

    public SchemaFetchScanOperator(
            PlanNodeId planNodeId,
            OperatorContext context,
            PathPatternTree patternTree,
            Map<Integer, Template> templateMap,
            ISchemaRegion schemaRegion,
            boolean withTags) {
        this.sourceId = planNodeId;
        this.operatorContext = context;
        this.patternTree = patternTree;
        this.schemaRegion = schemaRegion;
        this.templateMap = templateMap;
        this.withTags = withTags;
    }

    @Override
    public OperatorContext getOperatorContext() {
        return operatorContext;
    }

    @Override
    public TsBlock next() {
        if (!hasNext()) {
            throw new NoSuchElementException();
        }
        isFinished = true;
        try {
            return fetchSchema();
        } catch (MetadataException e) {
            logger.error("Error occurred during execute SchemaFetchOperator {}", sourceId, e);
            throw new RuntimeException(e);
        }
    }

    @Override
    public boolean hasNext() {
        return !isFinished;
    }

    @Override
    public boolean isFinished() {
        return isFinished;
    }

    @Override
    public PlanNodeId getSourceId() {
        return sourceId;
    }

    private TsBlock fetchSchema() throws MetadataException {
        ClusterSchemaTree schemaTree = new ClusterSchemaTree();
        List<PartialPath> partialPathList = patternTree.getAllPathPatterns();
        for (PartialPath path : partialPathList) {
            schemaTree.appendMeasurementPaths(schemaRegion.fetchSchema(path, templateMap, withTags));
        }

        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        try {
            // to indicate this binary data is database info
            ReadWriteIOUtils.write((byte) 1, outputStream);

            schemaTree.serialize(outputStream);
        } catch (IOException e) {
            // Totally memory operation. This case won't happen.
        }
        return new TsBlock(
                new TimeColumn(1, new long[]{0}),
                new BinaryColumn(
                        1, Optional.empty(), new Binary[]{new Binary(outputStream.toByteArray())}));
    }

    @Override
    public long calculateMaxPeekMemory() {
        return DEFAULT_MAX_TSBLOCK_SIZE_IN_BYTES;
    }

    @Override
    public long calculateMaxReturnSize() {
        return DEFAULT_MAX_TSBLOCK_SIZE_IN_BYTES;
    }

    @Override
    public long calculateRetainedSizeAfterCallingNext() {
        return 0L;
    }
}
